Project Summary Ventricular Tachycardia (VT) is a major public health problem associated with the majority of the 300,000 cases of sudden cardiac death in the United States each year. The best current therapy for VT involves drugs to reduce VT episodes plus implantation of a cardiac defibrilator (ICD) that prolongs life by terminating episodes of VT. Permanent cessation of VT can be achieved by ablation of the origin site(s) and exit pathway(s) of the arrhythmia. Despite the advantages of this technique, its adoption has been limited because it is currently appropriate only for the few patients with hemodynamically stable VT. This project will create a disruptive, less expensive, more effective, and safer system for minimally invasive identification and ablation of critical VT sites. It will combine the HeartLander (HL) epicardial walker with a non-invasive mapping technology and a flexible, needle-based, radio frequency ablation technique. In prior work we have demonstrated that these technologies can be integrated into a unified system and have also eliminated major technical risks of the technologies. In this Fast Track SBIR application, we propose to complete the integration of the technologies and then verify the efficacy of the system in a Yorkshire swine pig model of VT. Upon successful completion, we will be ready to advance to the clinic a simpler, safer, more reliable and less expensive approach to effectively treating the 500,000 annual cases of ventricular tachycardia. We will also have built the hardware and computation infrastructure to support additional mapping methodologies that will enable the treatment of complex multi-focal arrhythmias.